Oil burner with supplementary air intake



May 16, 1933. M. A. POWERS 1,909,007

OIL BURNER WITH SUPPLEMENTARY AIR INTAKE I Filed Nov. 30, 1931 llllIIIIlI H11 Z M -MM M6 191- ro/e/wsxs Patented May 16, 1933 PATENT OFFICE UNITED STATES mron A. rowaas, or nn'rnom MICHIGAN, ASSIGN'OR 'ro THE mm: srmm'r Aurom'ric company, or narnorr, MICHIGAN, A CORPORATION or MIGHIGAJI OIL BURNER WITH SUPPLEMENTARY AIR Application filed November 30, 1931.

My invention relates to air intakes for oil burners and has for its object an improvement in supplying air for combustion on installations where the rate of burning is above the normal capacity of the burner. It is well known that the vertical rotary type of oil burner,- wherein combustion occurs around the periphery'of a hearth ring, is capable of a wide range of operating capacity with good combustion quality and high operating efficiency. This fact enables a burner of comparatively small size to be applied to a wide range of boiler sizes. However, in view of the fact that most installations require but a low rate of combustion, it is impractical and the cost of production is too great to build all units of the same potentially high capacity when it is known that but a few will be operated at those high capacities. Likewise it is not desirable to build a larger size'burner in small numbers if the smaller unit can easily be adapted for such use.

Assume that a small burner of this type is quite capable of handling combustion rates up to, for example, 35 pounds of oil per hour. Above said rate, depending of course upon-the specific design of the unit, the air supply will become restricted and, although a larger amount of oil may pass through the burner and be properly placed, it will be impossible to burn it efliciently due to a lack of air.

In the past such deficiency at higher rates has been overcome by inserting a number of openings in the hearth surface through which atmosphere pressure conditions in the firebox. Thismethod, while widely used, was not very efi'ective and had numerous disadvantages. In the first lace, as the additional air supply was entirely controlled by draft conditions, it was impossible to maintain a constant air supply to match the constant oil feed to the firebox. When the draft was high, too much air entered and when the draft was low, too little air was supplied for proper burning. Too much air being the lesser of'the two ev1ls, field practice has always been to provide for a largeexcess air rate with the old'method. Secondly, the old method of supplying auxiliary an prevented the main additional air might be induced by the below Serial No. 577,882.

air supply from having the proper direction and velocity; because the air flow through the hearth openings was upward rather than outward and this upward flow of air inter fered with that coming from the fan preventing proper mixing at the edges. his is an important disadvantage, since the direction and velocity of the air stream on a rotary type burner is very important as combustion takes place only around the periphery of the co hearth, it is essential that the air be directed to the edge in proper quantity andwith sufficient velocity to mix with the oil vapors and burn completely. This is particularly important on large installations where the dis- :5

,tance from the burner head to the hearth-ring is large. In the third place, the openings were unevenly placed and the proportioning of air and oil was not constant around the periphery. In the fourth place, the hearth 7o openings were hard to make, generally consisting of pipe nipples connected in place, with the number installed, and the number plugged shut during adjustment being entirely up to the judgment of the service man.

None of the abovedisadvantages exists with the present invention and much improved operation results when itis used, as

will be presently evident. It provides an auxiliary air supply that is easily regulated and that does not interfere with the proper functioning of the burner.

In the accompanying'drawing, Fig. 1 is a perspective view of an oil burner with a supplementary air intake embodying my in- B5 vention, F ig.2 is a detail view of a ring for varying the amount of auxiliary air, and Fig. 3 is a partial vertical sectional view, parts of the burner being shown diagrammatically.

An annular castin 1 is provided with internal supporting us 2 which carry its Weight when dropped in place over the head of a standard burner, said fins 2 resting on a portion 3 of the usual burnenframe 4. The casting 1 is provided with an outwardly extending annular bottom flange 5, upon which the hearth pan 6 is carried and the hearth proper 7 built. ,The weight of the hearth is then carried by the burner in the conventional manner, the fins 2 on the'intake ring 1 trans- 100 mitting the weight to the burner frame 4. With the ring 1 in place it will be noted that an annular space 8 exists between said ring and the outside of. the burner frame 4. This space plus the capacity of the burner is sufficient to provide air for the maximum desired capacity. When less auxiliary air is required (and in all cases it is desirable to use as much fan air as possible due to its higher initial velocity) the intake area may be reduced by dropping in place in said annular space 8, one of several sizes of adjustment rings 9, said ring resting on the top of the burner frame 4. Thus accurate control of the amount of auxiliary air supply is possible. The largest adjustment ring 9 substantially fills the annular space 8 between the top of the burner frame and the inner periphery of the casting being provided with notches 10 to accommodate said fins. Of

course, this largest ring, since it practically closes off the entire area, is used only'when conditions after installation indicate no need for an auxiliary air supply and ordinarily some smaller size ring is required.-

This intake construction causes the air to enter in close proximity to the lower edges of the fan 11. While the fan body has a diameter approximating that of the burner frame (4) the blades themselves being of higher capacity extend outward a conslderable distance, projecting largely if not entirely over the annular area of the auxiliary air supply (8). As is well known, a definite negative air pressure exists just below the lower edges of fan blades of this type particularly where the air flow into the fan proper requires redirecting as in this case. The fan thus induces a large air flow through the auxillary intake, the amount of this flow being relatively constant and but little influenced by draft variations. My intake therefore allows accurate adjustment of the a1r flow which thereafter is practically unaffected by outside variables. i

The auxiliary air blends in with the main a1r flow and the two travel together at the proper velocity and in the proper direction for best mixing and combustion at the hearth ring. Thls is in direct contrast to the interference and improper flow of the air with the old method described above. In addition my deslgn assures a properly proportioned air feed to all portions of the' hearth.

As the annular casting requires practicall no effort to install, the saving in labor is considerable, while the resulting assembl is workmanlike in appearance and its effectiveness depends in no way upon the ability of the workman making the installation. 'The air adjustment by use of the pro er size restricting ring is readily accomplished and when once determinedv will not require further attention.

It is clear that the invention is capable of modifications in the details of construction without altering its essential character.

Therefore, I do not wish to be limited to the precise construction shown.

What I claim is:

1. A rotar oil burner comprising a frame, a fan rotata 1y mounted at the top of said frame, an annular member resting upon said burner frame and providing therewith an annular supplementary air intake and a hearth member supported on said annular member, said annular air intake being outside the burner frame in proximity to the lower edge of said fan member the blades of said fan overhanging a substantial portion of said annular air intake.

2. A burner frame, a'distributer head supported therein and including a fan projecting above said frame and arranged to spray oil. and air outwardly, an annular casting supported on a portion of said burner frame and forming an annular air intake space between it and the top portion of said frame, adjacent to the lower edge of said fan and a ring supported on the top of said frame in said annular space, whereby the size of said space may be varied by substituting a ring of different size.

, 3. A burner frame, a distributer head supported therein and including a fan projecting above said frame and arranged to spray oil and air outwardly, an annular casting supported on a portion of said burner frame and forming an annular air intake space between it and the top portion of said frame, adjacent to the lower edge of said fan and a ring supported on the top of said frame in said annular space, whereby the size of said space may be varied by substitutin a ring of different size, the blades of said an overhanging a substantial portion of said annular air intake.

Signed at Detroit, Michigan, this 20 day of November 1931.

MILTON A. POWERS. 

